Synthesis and incorporation of high-temperature ammonia-release agents in lit-end cigarettes

ABSTRACT

A tobacco smoking mixture and/or a cigarette wrapper with high-temperature ammonia-release agents therein are provided, wherein the high-temperature ammonia-release agents are present in an amount effective to reduce the cytotoxicity of gas phase or particulate matter formed during smoking of the cigarette. The high-temperature ammonia-release agents are capable of reducing the cytotoxicity of gas phase or particulate matter by evolving ammonia at temperatures greater than about 200° C., wherein the ammonia can interact with the particulate matter. Additionally, the high-temperature ammonia-release agents can be formed by heating an aqueous mixture of an iron precursor compound, an ammonia source compound and an acid.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application No.11/254,858, entitled SYNTHESIS AND INCORPORATION OF HIGH-TEMPERATUREAMMONIA-RELEASE AGENTS IN LIT-END CIGARETTES and filed on Oct. 21, 2005,which is now U.S. Pat. No. 7,690,387, which claims priority to U.S.Provisional Patent Application No. 60/621,540 entitled SYNTHESIS ANDINCORPORATION OF HIGH-TEMPERATURE AMMONIA-RELEASE AGENTS IN LIT-ENDCIGARETTES and filed on Oct. 25, 2004, the entire contents of both ofwhich are hereby incorporated by reference.

SUMMARY

As provided herein, high-temperature ammonia-release agents are providedfor use in smoking articles, such as cigarettes. By providinghigh-temperature ammonia-release agent, ammonia can be released duringcombustion or pyrolysis of tobacco and thus ammonia can be available toreact with smoke constituents formed during the combustion or pyrolysisof the tobacco or otherwise favorably influence the pyrolysis chemistry.

In an exemplary embodiment, a tobacco smoking mixture comprises tobacco;and at least one high-temperature ammonia-release agent, wherein the atleast one high-temperature ammonia-release agent is selected from thegroup consisting of an ammonium iron phosphate, an ammonium ironpyrophosphate, an ammonium aluminum phosphate, a metal amine complex,hydrates and mixtures thereof.

In another exemplary embodiment, a cigarette wrapper comprises a web; anoptional web-filler material; and at least one high-temperatureammonia-release agent supported on at least one of the web and theweb-filler material, wherein the at least one high-temperatureammonia-release agent is selected from the group consisting of anammonium iron phosphate, an ammonium iron pyrophosphate, an ammoniumaluminum phosphate, a metal ammine complex, hydrates and mixturesthereof.

In a further embodiment, a cigarette comprises a tobacco rod; acigarette wrapper surrounding the tobacco rod; and at least onehigh-temperature ammonia-release agent, wherein the at least onehigh-temperature ammonia-release agent is incorporated in or on at leastone of the tobacco rod and the cigarette wrapper, and wherein the atleast one high-temperature ammonia-release agent is selected from thegroup consisting of an ammonium iron phosphate, an ammonium ironpyrophosphate, an ammonium aluminum phosphate, a metal ammine complex,hydrates and mixtures thereof.

Also provided is a method of making a cigarette comprising (i)incorporating at least one high-temperature ammonia-release agent in oron at least one of tobacco cut filler and a cigarette wrapper, whereinthe at least one high-temperature ammonia-release agent is selected fromthe group consisting of an ammonium iron phosphate, an ammonium ironpyrophosphate, an ammonium aluminum phosphate, a metal ammine complex,hydrates and mixtures thereof; (ii) providing the tobacco cut filler toa cigarette making machine to form a tobacco column; (iii) placing thecigarette wrapper around the tobacco column to form a tobacco rod of acigarette; and (iv) optionally attaching a cigarette filter to thetobacco rod using tipping wrapper or other suitable method.

In a further embodiment, a method of making a high-temperatureammonia-release agent comprises forming an aqueous solution of an ironprecursor compound, an ammonia source compound, and orthophosphoricacid; and heating the solution to a temperature sufficient toprecipitate the high-temperature ammonia-release agents from thesolution, wherein the iron precursor compound is selected from the groupconsisting of oxidized iron particles, lepidocrocite, phosphosideriteand goethite.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1( a) shows an exemplary cigarette with a high-temperatureammonia-release agent supported on the base web of the wrapper. FIG. 1(b) shows a magnified view of a portion of the exemplary cigarette fromFIG. 1( a).

FIG. 2( a) shows an exemplary cigarette with a high-temperatureammonia-release agent supported on the base web of a first wrapper witha second outermost wrapper. FIG. 2( b) shows a magnified view of aportion of the exemplary cigarette from FIG. 2( a).

FIG. 3( a) shows an exemplary cigarette with a wrapper including ahigh-temperature ammonia-release agent. An inner web region of thewrapper contains high-temperature ammonia-release agent. FIG. 3( b)shows a magnified view of a portion of the exemplary cigarette from FIG.3( a).

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As provided herein, exemplary high-temperature ammonia-release agents,such as ammonium iron phosphates and pyrophosphates, ammonium aluminumphosphates, metal ammine complexes, hydrates and mixtures thereof, areincorporated into tobacco smoking mixtures and smoking articles toreduce the cytotoxicity of cigarette smoke by releasing ammonia uponsmoking of the tobacco smoking mixtures and/or the smoking articles.

Exemplary ammonium iron phosphates and pyrophosphates include ammoniumiron hydrogen phosphates, such as ammonium iron (III) bis-hydrogenphosphates and ammonium iron (III) pyrophosphates. Exemplary metalammine complexes include metal hexammine complexes, such as hexamminecobalt (III) phosphate tetrahydrate, chromium hexammine complexes, suchas hexammine chromium (III) phosphate tetrahydrate and rutheniumhexammine complexes, such as hexammine ruthenium phosphate tetrahydrate.

Exemplary lit-end cigarettes can include one or more high-temperatureammonia-release agents in tobacco rods and/or cigarette wrappers of thecigarettes. The high-temperature ammonia-release agent can introduceammonia into a combustion and/or pyrolysis region(s) of the cigarette inan amount effective to decrease the cytotoxicity of particulate matterformed during smoking (i.e., during combustion and/or pyrolysis oftobacco and/or cigarette wrapper). Mixtures of high-temperatureammonia-release agents can be used.

Cigarette smoke comprises solid and gaseous phases (e.g., tar andgas-phase smoke). Combustion by-products can be produced in thecombustion/pyrolysis regions of a cigarette during smoking (e.g., fromtobacco combustion) and are typically present in both the solid andgaseous phases of cigarette smoke. For example, peroxy radicals, alkoxyradicals, super-oxides, aldehydes, and the like can be present in thetar or gas phase of the cigarette smoke. The high-temperatureammonia-release agents can introduce ammonia into the combustion and/orpyrolysis zones where combustion by-product compounds can be formed.

High-temperature ammonia-release agents preferably evolve ammonia uponcombustion/pyrolysis of a smoking article, such as a cigarette. Releaseof ammonia occurs when the high-temperature ammonia-release agentsencounter elevated temperatures based upon heat from the combustionand/or pyrolysis of tobacco during smoking. The ammonia, which isintroduced to and is present in the combustion/pyrolysis regions of thecigarette, can react with cytotoxic compounds and/or precursors thereofin order to decrease the cytotoxicity of gas phase, tar and otherparticulate matter formed during smoking.

Ammonia that is introduced directly to the combustion/pyrolysis zone ofa lit-end cigarette during smoking can decrease the cytotoxicity ofvarious compounds in particulate matter (e.g., tar). Without wishing tobe bound by theory, the introduction of ammonia to the combustion and/orpyrolysis zone of a lit-end cigarette during smoking can disrupt theformation processes of various compounds. Additionally, ammonia is afree amine group (i.e., it can form free amino groups), which can reactwith carbonyl groups via Maillard-type reactions resulting in decreasedcytotoxicity of particulate matter. Ammonia can also condense withcarbonyl groups, and after double-bond migration, can provide “bound”amine groups for further reaction with other carbonyl-group containingsubstances.

Preferably, the high-temperature ammonia-release agents have minimaleffects on the physical properties of mainstream smoke. For example, theodor, taste and appearance of mainstream smoke in a cigarette containingthe high-temperature ammonia-release agent should be substantiallyidentical to the odor, taste and appearance of mainstream smoke in aconventional cigarette.

High-temperature ammonia-release agents can be provided with a lowsolubility in water so as to be compatible with paper-making processes.For example, a high-temperature ammonia-release agent can be providedwhich is substantially insoluble in an aqueous dispersion used to makecigarette wrappers.

Additionally, a high-temperature ammonia-release agent that is stable inliquids such as water and alcohols can be incorporated into a tobaccosmoking mixture (e.g., tobacco cut filler) via an aqueous or non-aqueousdispersion of the high-temperature ammonia-release agent to providerelatively uniform distribution of the high-temperature ammonia-releaseagents in a smoking article. The high-temperature ammonia-release agentcan be provided in liquid or solid form, wherein when provided in solidform, the high-temperature ammonia-release agents can be finely dividedand can comprise particles having an average particle size of less thanabout 10 microns.

By “incorporated in” is meant that high-temperature ammonia-releaseagents are dispersed throughout a tobacco smoking mixture and/or withina cigarette wrapper. In exemplary embodiments, high-temperatureammonia-release agents are reasonably uniformly incorporated in atobacco smoking mixture and/or a cigarette wrapper material during theformation of the tobacco smoking mixture and/or the formation of thecigarette wrapper material, respectively. By “incorporated on” is meantthat the high-temperature ammonia-release agent is dispersed on anexposed surface of a support such as tobacco and/or a cigarette wrappermaterial. Particles of a high-temperature ammonia-release agent that areincorporated in or on cut filler or cigarette wrapper can be supportedby the cut filler or cigarette wrapper.

In exemplary embodiments, high-temperature ammonia-release agentsrelease ammonia at temperatures greater than about 200° C., morepreferably greater than about 600° C. Exemplary high-temperatureammonia-release agents include, as mentioned above, ammonium ironphosphates and pyrophosphates, ammonium aluminum phosphates and metalammine complexes, each of which can release ammonia at temperaturesgreater than about 200° C.

In exemplary embodiments, as mentioned above, the high-temperatureammonia-release agent can include ammonium iron phosphates (e.g.,phosphates, pyrophosphates, polyphosphates as well as their hydrates),ammonium aluminum phosphates, metal ammine complexes and mixturesthereof. As used herein, the exemplary high-temperature ammonia-releaseagents are intended include both unhydrated and hydrated species of thecompounds used as high-temperature ammonia-release agents.

In exemplary embodiments, ammonium iron bis-hydrogen phosphate(NH₄Fe(HPO₄)₂) and/or ammonium iron pyrophosphate (NH₄FeP₂O₇) can beused to release ammonia (typically about 6 to 10% by weight). In theseexemplary embodiments, the high-temperature ammonia-release agents canrelease ammonia through their decomposition temperatures greater thanabout 600° C. The release can occur based upon a disassociation of oneor more ammonium cations and the concomitant elimination of theirassociated phosphoric acid groups. Exemplary ammonium iron(pyro)phosphate phases are listed in Table 1.

TABLE 1 Ammonium Iron (Pyro)Phosphates a. (NH₄)₉Fe(III)(P₂O₇)₃•9H₂O b.(NH₄)₅Fe(III)(P₂O₇)₂•4H₂O c. (NH₄)₆Fe(II)(P₂O₇)₂•6H₂O d. (NH₄)Fe(III)P₂O₇•1.5H₂O e. (NH₄)₂Fe(II) P₂O₇•2H₂O f. (NH₄)Fe(III) P₂O₇ g.(NH₄)Fe(III)₃(P₆O₂₀)•10H₂O h. (NH₄)Fe(III)(HPO₄)₂ i.(NH₄)Fe(III)(HPO₄)₂•0.5H₂O j. (NH₄)₃Fe(III)(HPO₄)(P₂O₇)•H₂O k.(NH₄)Fe₂(PO₄)₂(OH)•2H₂O l. (NH₄)₂Fe(III)P₂O₇(OH)•2H₂O

In exemplary embodiments, high-temperature ammonia-release agents can beformed by forming an aqueous solution of one or more ammonia sourcecompounds, one or more iron precursor compounds, and an orthophosphoricacid, and then heating the solution to a temperature sufficient toprecipitate high-temperature ammonia-release agents therefrom.

Exemplary ammonia source compounds that can be used to formhigh-temperature ammonia-release agents include, but are not limited to,ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammoniagas, ammonium carbonate, ammonium bicarbonate, ammonium hydroxide andurea.

Exemplary iron precursor compounds that can be used to formhigh-temperature ammonia-release agents include, but are not limited to,oxidized iron particles, lepidocrocite, phosphosiderite and goethite.Other exemplary iron precursor compounds can be derived from iron metalsuch as iron metal flakes that are oxidized. It is noted thatlepidocrocite can be derived from iron oxide hydroxide (FeOOH) andphosphosiderite is a stable polymorph of iron (III) phosphate dihydrate,FePO₄.2H₂O. The phosphosiderite can be prepared via reaction betweeniron oxide hydroxide (FeOOH) and orthophosphoric acid, H₃PO₄. Forexample, iron oxide hydroxide can be boiled in an aqueous solution oforthophosphoric acid and the resulting precipitate can be filtered,washed with water, and dried at low temperature (e.g., about roomtemperature) to give the phosphosiderite phase. Details and results fromthe synthesis of phosphosiderite from iron oxide hydroxide are shown inTable 2. The yield of phosphosiderite was in excess of 90%.

TABLE 2 Synthesis of phosphosiderite, FePO₄•2H₂O Reflux time Run FeOOH(g) H₃PO₄ (g) Water (mL) (min) Yield (%) 1 30 127 254 60 96 2 195 520500 80 93

After forming iron precursor compounds, such as phosphosiderite, andproviding the one or more ammonia source compounds and theorthophosphoric acid, high-temperature ammonia-release agents can beformed therefrom. In exemplary embodiments, high-temperatureammonia-release agents can be synthesized hydrothermally or underatmospheric pressure.

For example, an iron precursor (e.g., phosphosiderite) can first becombined in a Teflon-lined reactor cell with an acidic aqueous solution(of orthophosphoric acid, H₃PO₄), and an ammonia source compound (e.g.,ammonium dihydrogen phosphate, NH₄H₂PO₄). Then, in an open (i.e.,un-pressurized vessel) at about 100° C., by stirring the iron precursor(phosphosiderite) into a boiling aqueous solution with ammoniumdihydrogen phosphate and an excess of orthophosphoric acid, ahigh-temperature ammonia-release agent (e.g., ammonium iron (III)bis-hydrogen phosphate hydrate can be precipitated therefrom. Theformation of ammonium iron (III) bis-hydrogen phosphate hydrate fromphosphosiderite is shown in Equation 2, where x can be 0.0 or 0.5.FePO₄.2H₂O+NH₄H₂PO₄→NH₄Fe(HPO₄)₂ .xH₂O+(2-x)H₂O  Eqn. 2

After filtering, washing and drying the precipitate, a free-flowing,crystalline high-temperature ammonia-release powder can be achieved.Details of the above exemplary synthesis are shown in Table 3. It isnoted that from this exemplary synthesis, a yield of greater than 95%ammonium iron (III) bis-hydrogen phosphate hydrate was achieved.

TABLE 3 Synthesis of NH₄Fe(HPO₄)₂•xH₂O Reflux FePO₄•2H₂O NH₄H₂PO₄ H₃PO₄H₂O time Yield Run (g) (g) (g) (mL) (min) (%) 1  37 47 58 250 255 97 2*37 47 58 250 270 96 *Run #2 was refluxed while stirring at 120 rpm,while Run #1 was not stirred.

Alternatively, a high-temperature ammonia-release agent can be preparedvia a “one pot” synthesis. For example, first, an aqueous solution ofiron oxide hydroxide (FeOOH) and orthophosphoric acid can be heated toform phosphosiderite, wherein, preferably, an excess of acid is used.After precipitation of a phosphosiderite intermediate, ammoniumdihydrogen phosphate can be added to precipitate an ammonium iron saltand form ammonium iron (III) bis-hydrogen phosphate hydrate using the“one pot” synthesis is shown by Equation 3.FeOOH+H₃PO₄+NH₄H₂PO₄→NH₄Fe(HPO₄)₂ .xH₂O+(2-x)H₂O  Eqn. 3

By way of example, approximately 117 grams of FeOOH was combined with afirst solution of 85% H₃PO₄ (1130 grams) and about 460 grams of NH₄H₂PO₄in 2 liters of water to form a second solution. Next, the secondsolution can be refluxed for about 3 hours under constant stirring atabout 170 rpm, wherein a precipitate yield of nearly 100% can beobtained after filtering, washing and drying.

In another exemplary “one pot” synthesis method, iron oxide hydroxideprecursor (e.g., Bayferrox® 943 from Bayer AG, Germany) can be used asthe iron precursor material. Initially, approximately 45 grams of theiron oxide hydroxide can be combined with 86% H₃PO₄ (177 grams) in 400mL of boiling water under constant stirring. After about 60 minutes,about 115 grams of NH₄H₂PO₄ was added under continued reflux andcontinued stirring. Approximately 100% yield of a high-temperatureammonia-release agent ammonium iron salt can be obtained afterfiltering, washing and drying precipitate.

In another exemplary embodiment Ammonium iron (III) pyrophosphate,(NH₄)Fe(III)P₂O₇, can be synthesized by hydrothermally treatingphosphosiderite under more vigorous conditions (e.g., by increasing thetemperature, pressure and reflux time) compared to those used to formthe phosphate according to Equation 2 above. In an embodiment, a static(i.e., without stirring) hydrothermal synthesis of the pyrophosphatephase can be carried out in a Teflon-lined stainless steel vessel.Alternatively, stirring during the synthesis can be provided to improvethe yield of free-flowing powder (as opposed to an agglomerate). It isnoted that exemplary high-temperature ammonia-release agents weresynthesized, wherein maximum external temperatures and internalpressures in exemplary vessels are reported in Table 4.

TABLE 4 Hydrothermal Synthesis of Ammonium Iron (III) (Pyro)phosphatesRun Run Run Run 1 2 Run 3 Run 4 5 6 FePO₄•2H₂O (g) 19 19 19 19 38 75NH₄H₂PO₄ (g) 23 46 115 60 57 69 (NH₄)₂HPO₄ (g) 0 0 0 66 0 0 H₃PO₄ 45 930 0 92 92 (g) H₂O (mL) 90 50 100 100 50 50 Time (hr) ~25 ~72 ~48 72 93120 T_(max) (external) (° C.) 280 315 318 315 315 315 P_(max) (psig) 320370 570 650 500 400 Yield (g) 25 23 22 20 46 100 Product Phos PyroPhos + Pyro + Pyro Pyro Pyro Hydphos

Identification of the crystalline phases present in the product was doneusing x-ray diffraction. Referring to Table 4, the product “Phos” isintended to indicate ammonium iron (III) bis-hydrogen phosphate, “Pyro”is intended to indicate ammonium iron (III) pyrophosphate and “Hydphos”is intended to indicate ammonium iron (III) hydroxide phosphatedihydrate, (NH₄)Fe₂(PO₄)₂(OH).2H₂O.

The product from Run #1, which shows the result of an experiment carriedout at the lowest temperature, pressure and time of the six exemplaryembodiments shown, is ammonium iron (III) bis-hydrogen phosphatehydrate. At the highest reactor temperature (i.e., greater than about300° C.) and a maximum internal pressure (i.e., greater than about 350psig) (i.e., Run #2) of the six exemplary embodiments shown, the productfrom is ammonium iron (III) pyrophosphate. In the product from Run #3both the phosphate and pyrophosphate phases were detected. In theproduct from Run #4 pyrophosphate phase and an ammonium iron hydroxidephosphate phase were detected.

Other exemplary high-temperature ammonia-release agents includehexammine complexes of various transition metals. Ammine complexes,which may coordinate up to 6 ammonia molecules per transition metal ion(e.g., cobalt, chromium or ruthenium) can release up to about 30%ammonia or more by weight. Heating ammine complexes can initially causedehydration at about 100° C., however, heating to temperatures exceedingabout 100° C. can cause decomposition, which can result in a decrease inthe oxidation state of the transition metal center (i.e., the metal canbe reduced). The decomposition of ammine complexes can be represented byEquation 1, which shows the release of ammonia, water and nitrogen froma hexammine complex (e.g., hexamminecobalt (III) phosphate Co(NH₃)₆PO₄at about 230° C.).6Co(NH₃)₆PO₄→3CO₂P₂O₇+34NH₃+3H₂O+N₂  Eqn. 1

The thermal decomposition of hexammine cobalt (III) phosphatetetrahydrate to form ammonia is disclosed in Gmelin's Handbuch derAnorganischen Chemie, 8. Auflage, Kobalt, Teil B, page 66, the contentof which is incorporated herein by reference.

Hexammine complexes can be prepared via reaction between a hexamminemetal chloride and a water soluble phosphate. For example, crystals ofhexammine cobalt (III) phosphate tetrahydrate can be obtained byfiltering, washing and drying the precipitate resulting from theaddition of diammonium phosphate to an aqueous solution of hexamminecobalt (III) chloride. Optionally, the pH of the solution can beincreased by the addition of a base such as ammonia.

By way of example, cobalt chloride hexahydrate (70 g) can be combinedwith ammonium chloride (34 g) and ammonium hydroxide (190 g) in anaqueous solution (500 mL water). Approximately 30 grams of activatedcarbon (to catalyze hexamine cobalt (III) formation) can then be addedto the solution, which can then be treated with a vigorous stream of airor oxygen at room temperature for about 4 hours. The precipitate canthen be filtered, washed with water, and the filtrate treated with anaqueous solution of diammonium hydrogen phosphate, (NH₄)₂HPO₄, (24 gramsin 150 mL H₂O) for about 1 hr to obtain an approximately 25% yield ofhexammine cobalt (III) orthophosphate tetrahydrate, (Co(NH₃)₆)PO₄.4H₂Ofrom the filtrate.

Additionally, the activated carbon/hexammine cobalt (III) trichloridefilter cake, as provided above, can be leached with water (760 mL) underair agitation for about 40 minutes, wherein residual activated carboncan subsequently be removed by filtration. From this filtrate, anadditional 25% yield of hexammine cobalt (III) orthophosphatetetrahydrate can thus be obtained by adding diammonium hydrogenphosphate (25 g dissolved in minimal water), thus resulting in a totalyield that was approximately 50%.

In a further example, crystals of hexammine chromium (III) phosphatetetrahydrate can be obtained via the addition of diammonium phosphate toa solution of hexammine chromium (III) chloride. Advantageously, incontrast to the hexammine cobalt (III) phosphate, which can thermallydecompose to give ammonia, water and nitrogen according to Equation 1,thermal decomposition of a single mole of the chromium complex canproduce six moles of ammonia, without causing oxidation of othermolecules.

As provided herein, exemplary tobacco smoking mixtures include at leastabout 50% by weight of tobacco (and thus, an effective amount ofhigh-temperature ammonia-release agents of up to about 50%) based on thetotal weight of the tobacco smoking mixture. The tobacco typicallyfunctions as fuel in the combustion and/or pyrolysis of the tobaccosmoking mixture. Examples of suitable types of tobacco includeflue-cured, Bright, Burley, Maryland or Oriental tobaccos, the rare orspecialty tobaccos, and blends thereof. The tobacco can be provided inthe form of cut tobacco leaf filler, processed tobacco materials such asvolume expanded or puffed tobacco, processed tobacco stems such ascut-rolled or cut-puffed stems, reconstituted tobacco materials orblends thereof. The tobacco can also include tobacco substitutes such assynthetic tobacco. Generally the tobacco used to form a cigarette isaged.

In cigarette manufacture, the tobacco can be employed in the form of cutfiller, i.e., in the form of shreds or strands cut into widths rangingfrom about 1/10 inch to about 1/20 inch or even 1/40 inch. The lengthsof the strands range from between about 0.25 inch to about 3.0 inch.

The tobacco smoking mixture may optionally include additives to improvevarious characteristics of the tobacco during smoking. For example,taste modifiers may be added to the tobacco smoking mixture to improveits flavor. In addition, burn additives may be used to impart desirableburn characteristics to the tobacco. Examples of burn additives include,but are not limited to, sodium fumarate, sodium citrate, potassiumcitrate, potassium succinate, potassium monohydrogen phosphate, andpotassium dihydrogen phosphate.

The tobacco smoking mixture may be manufactured using any suitabletechnique. The high-temperature ammonia-release agent may be added totobacco cut filler, which in turn can be supplied to a cigarette-makingmachine, or the high-temperature ammonia-release agent can beincorporated on a pre-formed tobacco column prior to wrapping acigarette wrapper around the tobacco column. For example, according toone embodiment, a method for manufacturing the tobacco smoking mixturecomprises the step of spraying tobacco with at least onehigh-temperature ammonia-release agent in liquid or solid form.

To facilitate spraying of solid high-temperature ammonia-release agents,the agent can be added to a liquid carrier to form a slurry or asolution, and the slurry or solution can be sprayed onto the tobacco.The tobacco smoking mixture containing high-temperature ammonia-releaseagents can then be processed for use in a cigarette (or other smokingarticle).

Slurry or solution with high-temperature ammonia-release agents thereincan include any non-reactive liquid or liquid mixture suitable fordispersing and dispensing (e.g., spraying) high-temperatureammonia-release agents. A preferred liquid is water (e.g., deionizedwater), though other liquids, such as alcohols, can be used. Theconcentration of high-temperature ammonia-release agents in the slurryor solution can be any amount suitable for dispensing the slurry orsolution onto tobacco. Slurry or solution of high-temperatureammonia-release agents in a liquid can comprise greater than about 1%,more preferably greater than about 5% by weight of the high-temperatureammonia-release agents.

Alternatively, solid high-temperature ammonia-release agents can beprovided as powder or particulate matter and can be mixed with thetobacco to form a tobacco smoking mixture before processing the tobaccosmoking mixture for use in a cigarette (or other smoking article). Forexample, moistened tobacco cut filler or a slurry of reconstitutedtobacco material can be dusted with a powdered high-temperatureammonia-release agent prior to forming the tobacco material into atobacco rod.

Another technique for incorporating particles of a high-temperatureammonia-release agent in a tobacco smoking mixture involves adding thehigh-temperature ammonia-release agent to a slurry of ingredients usedto make reconstituted tobacco. Particles of high-temperatureammonia-release agent can be added to the in any suitable amount, thenthe high-temperature ammonia-release agent containing reconstitutedtobacco slurry can be formed into reconstituted tobacco sheet and cut tosize for incorporation as 100% filler of a tobacco rod or the can beadded to tobacco rod filler material and the mixture formed into atobacco rod.

Preferably, a total amount of high-temperature ammonia-release agent inthe tobacco smoking mixture is an amount effective to reduce thecytotoxicity of tar and other particulate matter generated from thecombustion/pyrolysis of tobacco and/or cigarette wrapper. The tobaccosmoking mixture can comprise up to about 10% by weight or more of ahigh-temperature ammonia-release agent, based on the total weight of themixture. A cigarette can be formed from a tobacco column comprising thetobacco smoking mixture.

According to a further embodiment, a high-temperature ammonia-releaseagent is incorporated in and/or on a cigarette wrapper. Preferably, thecigarette wrapper is used to form a lit-end cigarette. Ahigh-temperature ammonia-release agent can be incorporated in or on thewrapper of a lit-end cigarette in addition to and/or in lieu ofincorporation of the high-temperature ammonia-release agent in thetobacco smoking mixture. By incorporating the high-temperatureammonia-release agent in the cigarette wrapper, the high-temperatureammonia-release agent can evolve ammonia upon combustion/pyrolysis ofthe cigarette. The ammonia formed by the high-temperatureammonia-release agent can decrease the cytotoxicity of gas phase, tarsand other particulate matter formed in the combustion/pyrolysis regionsof the cigarette during smoking.

Referring to FIG. 1( a), an exemplary embodiment cigarette 100 has atobacco rod portion 90, an optional filtering tip 92 and a cigarettewrapper 104 which can include high-temperature ammonia-release agentstherein or thereon. Also, as shown in FIG. 1( a), the tobacco rodportion 90 includes a column of tobacco 102 that is enwrapped with thecigarette wrapper 104.

The high-temperature ammonia-release agent 110 can be incorporateddirectly into a cigarette wrapper (e.g., in place of a web-fillermaterial) or the high-temperature ammonia-release agent can beincorporated into the cigarette wrapper by supporting thehigh-temperature ammonia-release agent on the web-filler material. Theweb-filler material can include an oxide, a carbonate, or a hydroxide ofa Group II, Group III or Group IV metal, or the web-filler material canbe selected from the group consisting of CaCO₃, TiO₂, silicates such asSiO₂, Al₂O₃, MgCO₃, MgO, Mg(OH)₂ and hydromagnesite.

As shown in expanded view in FIG. 1( b), the cigarette wrapper 104includes a web of fibrous cellulosic material 106 in which is typicallydispersed particles of a web-filler material 108, such as calciumcarbonate (CaCO₃). In practice, the web-filler material 108 serves as anagent for controlling the permeability of the wrapper 104 (measuredtypically in units of Coresta, which is defined as the volume of air,measured in cubic centimeters, that passes through one square centimeterof material in one minute at a pressure drop of 1.0 kilopascals) andoptionally serves as a support for particles of a high-temperatureammonia-release agent 110.

In a preferred embodiment of a cigarette wrapper comprising ahigh-temperature ammonia-release agent, the high-temperatureammonia-release agent is an ammonium iron phosphate optionally supportedon particles of a calcium carbonate web-filler material. In anotherpreferred embodiment, a total amount of high-temperature ammonia-releaseagent in the cigarette wrapper is an amount effective to reduce thecytotoxicity of tar and other particulate matter generated from thecombustion/pyrolysis of tobacco and/or cigarette wrapper during smoking.

In one approach, a high-temperature ammonia-release agent 110, such asammonium iron phosphate, is supported by web-filler material 108, suchas CaCO₃, by forming an aqueous slurry of the high-temperatureammonia-release agent and the web-filler material. The CaCO₃ can be thesame as the filler material used in the papermaking process, such asALBACAR 5970 commercially available from Specialty Minerals ofBethlehem, Pa. The slurry is spread, for example, using a doctor'sblade, and then dried to evaporate the water. The slurry can be dried byexposure to air and optionally a heat source, such as radiation lamp at75° C., although other methods such as vacuum filtering followed bydrying can also be used to dry the slurry. The wet or dried slurry caninclude a high-temperature ammonia-release agent modified web-filler,which can be incorporated in a cigarette wrapper.

A high-temperature ammonia-release agent modified web-filler can beincorporated in the wrapper through conventional papermaking processes.For example, the high-temperature ammonia-release agent modifiedweb-filler can be used as all or part of the filler material in thepapermaking processes or can be distributed directly onto the wrapper,such as by spraying or coating onto a wet or dry base web.Alternatively, a high-temperature ammonia-release agent can beincorporated in a wrapper as filler material (i.e., in lieu of aconventional filler material such as calcium carbonate).

A wrapper can be any wrapping adapted to surround the cut filler,including wrappers containing flax, hemp, kenaf, esparto grass, ricestraw, wood pulp, cellulose and so forth. When supplied to thecigarette-making machine, the wrapper can be supplied from a singlebobbin in a continuous sheet (a mono-wrap) or from multiple bobbins (amulti-wrap, such as a dual wrap from two bobbins). Further, the wrappercan have more than one layer in cross-section, such as in a bi-layerpaper as disclosed in commonly-owned U.S. Pat. No. 5,143,098, the entirecontent of which is herein incorporated by reference. Thehigh-temperature ammonia-release agent 110 can be provided in thecigarette wrapper in addition to or in lieu of web-filler material 108.

Alternatively, the cigarette wrapper can include at least onehigh-temperature ammonia-release agent on the cigarette wrapper 104supported directly on the cigarette wrapper. For example,high-temperature ammonia-release agents can be sprayed in liquid orparticle form onto a surface a cigarette wrapper to form a uniformdistribution of the high-temperature ammonia-release agents on thecigarette wrapper.

Further and in the alternative to incorporating a high-temperatureammonia-release agent into the web of the wrapper in a papermakingprocess, it is contemplated that the paper (wrapper) can be manufacturedfirst and the high-temperature ammonia-release agent can subsequently beincorporated on one or more surfaces of the paper. For example, thehigh-temperature ammonia-release agent can be distributed directly ontothe wrapper, such as by spraying or coating onto wet base web, theintermediate web or the finished web. The high-temperatureammonia-release agent can be coated onto the outer and/or inner surfaceof a cigarette wrapper, though a wrapper having high-temperatureammonia-release agent incorporated on an inner surface thereof ispreferred. The inner surface of a cigarette wrapper is adapted to becloser to the tobacco column than the outer surface of a cigarettewrapper. If desired, a wrapper incorporating a high-temperatureammonia-release agent can be used at other locations and/or for any ofthe wrapper layers of a cigarette.

When incorporated in or on a cigarette wrapper, a preferred amount ofthe high-temperature ammonia-release agent is equal to from about 5% to60%, more preferably about 20% to 50% of the final wrapper weight.

The cigarette wrapper may be a one-wrapper construction, a multi-wrapperconstruction or a multi-layer single-wrap construction. FIGS. 2( a) and2(b) show a cigarette with a high-temperature ammonia-release agentsupported on the base web of a first wrapper with a second outermostwrapper. In the FIG. 2( a) embodiment, the cigarette 100 includes acigarette tobacco column 102 surrounded by a first inner wrapper 112. Asshown in expanded view in FIG. 2( b), the first wrapper 112 includes aweb 114. A web-filler material 116 and a high-temperatureammonia-release agent 118 are supported on the web 114. If desired, thefirst wrapper 112 can include a high-temperature ammonia-release agent118 that is supported on particles of web-filler material (not shown).

The cigarette 100 has a second wrapper 120 surrounding the first wrapper112. The total amount of high-temperature ammonia-release agent 118 inthe second outer wrapper 120 is preferably less than 1 mg for a givensingle cigarette 100, however the second wrapper 120 can also notinclude any high-temperature ammonia-release agents so as to provide anappearance to the cigarette 100 that is not affected by any colorationfrom the high-temperature ammonia-release agent.

A total amount of high-temperature ammonia-release agent in the firstwrapper can be from about 10 to 100 mg and in the second wrapper can beless than 1 mg, preferably 0 mg and/or a ratio, in weight percent, ofhigh-temperature ammonia-release agent in the second wrapper 120 to thehigh-temperature ammonia-release agent in the first wrapper 112 can beless than about 0.25.

Referring again to the embodiment of FIGS. 2( a) and 2(b), the innerwrapper and the outer wrapper are individual wrappers formed in separatepapermaking processes and later wrapped around tobacco cut filler toform a cigarette tobacco rod. The inner wrapper, the outer wrapper orboth wrappers can include a high-temperature ammonia-release agent.

In examples where both wrappers include a high-temperatureammonia-release agent, the specific high-temperature ammonia-releaseagent and the loading in each wrapper can be the same or different.Because the addition of a high-temperature ammonia-release agent candiscolor the wrapper, e.g., the wrapper becomes non-white or brown, foraesthetic reasons an outer wrapper that is a conventional color, e.g.,white, can be placed around the inner wrapper. Both the inner wrapperand the outer wrapper can be selected to give a desired cigaretteperformance with respect to cigarette properties, such as puff count,tar, burn rate, and ash appearance.

FIG. 3( a) shows an embodiment of a cigarette with a wrapper including ahigh-temperature ammonia-release agent. In the FIG. 3( a) embodiment,the cigarette 100 includes a cigarette tobacco column 102 and a wrapper122. As shown in expanded view in FIG. 3( b), the wrapper 122 includes aweb 124 and incorporated in the web are a web-filler material 126 and ahigh-temperature ammonia-release agent 128. The web-filler material 126and the high-temperature ammonia-release agent 128 are supported on theweb. If desired, the high-temperature ammonia-release agent 128 can besupported on the web-filler material, which can be supported on the web.The wrapper 122 has a radially inner portion 130 and a radially outerportion 132, the radially inner portion 130 having a first loading ofthe high-temperature ammonia-release agent 128 and the radially outerportion 132 having a second loading of the high-temperatureammonia-release agent 128.

In an exemplary cigarette, the first loading of the high-temperatureammonia-release agent can be greater than the second loading of thehigh-temperature ammonia-release agent. For example, the first loadingof the high-temperature ammonia-release agent in the wrapper for a givensingle cigarette 100 can be up to 100 mg and the second loading of thehigh-temperature ammonia-release agent can be less than 1 mg. In theFIG. 3( a) embodiment, the high-temperature ammonia-release agent can bedistributed throughout the wrapper such that when the wrapper is formedabout a tobacco column to form a tobacco rod of a cigarette, the loadingof the high-temperature ammonia-release agent decreases in the radialdirection. However, the axial loading of the high-temperatureammonia-release agent (e.g., along the length of the tobacco rod) canalso be substantially uniform.

The wrapper can be any suitable conventional wrapper. For example, apreferred wrapper can have a basis weight of from about 15 g/m² to 75g/m² and a permeability of from about 2 Coresta units to about 200Coresta units. More preferably, the wrapper has a basis weight fromabout 20 g/m² to 50 g/m² and the permeability is about 10 to 100 Corestaunits. However, any suitable basis weight for the wrapper can beselected. For example, a higher basis weight, e.g., 35 to 45 g/m², cansupport a higher loading of high-temperature ammonia-release agent. If alower loading of a high-temperature ammonia-release agent is selected,then a lower basis weight wrapper can be used.

Other permeabilities of the wrapper (as measured by Coresta units) canbe selected based on the application and location of the wrapper. Forexample, in multi-layer wrappers the permeability of a first layer canbe up to 1,000 Coresta units, although a permeability that is lower orhigher can be used. Thickness of single-layer wrapper can preferably befrom about 15 to 100 microns, more preferably from about 20 to 50microns. Additional layers in a multi-layer wrapper can be from 0.1 to10 times the permeability of the first layer and can have a thickness offrom 0.1 to 2 times the thickness of the first layer. Both thepermeability and the thickness of the first layer and the second layercan be selected to achieve a desired total air permeability and totalthickness for the cigarette.

According to still yet another method for incorporating high-temperatureammonia-release agents in a smoking article, the high-temperatureammonia-release agents can be incorporated in either or both of tobaccosmoking mixture and/or a cigarette wrapper. Therefore, exemplaryembodiments of cigarettes and methods of making cigarettes can include atobacco rod portion of a cigarette with a high-temperatureammonia-release agent incorporated in the tobacco cut filler and/or in acigarette wrapper that over-wraps the tobacco.

The location, distribution and quantity of high-temperatureammonia-release agent in the wrapper and/or cut filler can be selectedas a function of the temperature and airflow characteristics exhibitedin a burning cigarette in order to minimize the cytotoxicity of thegenerated particulate matter or gas phase while maintaining desiredorganoleptic properties. For example, the solid coal in a cigarettereaches the peak temperature of greater than 850-900° C. at about theburn zone, e.g., within about 2 mm of the burn zone, and is at 300° C.to 400° C. within 2 to 3 mm of the burn zone. Thus, a high-temperatureammonia-release agent can be selected that operates in a giventemperature range, and a tobacco smoking mixture and/or wrapper can bemanufactured in which high-temperature ammonia-release agent can beincorporated in order to provide the desired reduction in cytotoxicityof tar and other particulate matter formed during smoking.

Exemplary high-temperature ammonia-release agents can be positionedalong the entire axial length of the anticipated burn zone, e.g., notonly at the distal end of the cigarette, and can be active from the litend to the filter end during smoking of the cigarette. The distributionof the high-temperature ammonia-release agent preferably providessufficient contact time between pre-condensed particulate matter (e.g.,tar) and the thermally generated ammonia to substantially decrease thecytotoxicity of the particulate matter.

In a further example, a mixed high-temperature ammonia-release agent,e.g., a combination of two or more high-temperature ammonia-releaseagent compositions (each of which release ammonia at differenttemperature ranges) or overlapping temperature ranges can be used tobroaden the temperature range at which ammonia is generated. Forexample, a mixed high-temperature ammonia-release agent may operate tointroduce ammonia in both the combustion and pyrolysis regions.

Although the high-temperature ammonia-release agent is described hereinas having an operating temperature, the phrase “operating temperature”refers to the preferred temperature for creation of ammonia. Thehigh-temperature ammonia-release agent may still operate to decrease thecytotoxicity of gas phase, tar and other particulates generated viatobacco combustion outside the described temperature range.

In addition, any of the wrappers or methods described herein can includeadditional additives conventionally used in wrappers for cigarettes.These additives can include, for example, optional filler materials,flavor additives, additives to control the appearance, e.g., color, ofthe wrapper, additives to control the burn rate of the wrapper, and/oradditives to result in a desired ash appearance and/or web-fillers usedin cigarette wrapper. Burn additives such as alkali metal salts ofcarboxylic acids or of phosphoric acids can be applied to the wrapper toadjust or control the burn rate of a cigarette comprising the wrapper.For example, burn additives can be applied in amounts ranging from about2% to about 15% by weight of the wrapper.

An embodiment relates to a method of making a cigarette comprising thesteps of (i) incorporating a high-temperature ammonia-release agent inat least one of tobacco cut filler and a cigarette wrapper; (ii)providing the tobacco cut filler to a cigarette making machine to form atobacco column; (iii) placing the cigarette wrapper around the tobaccocolumn to form a tobacco rod of a cigarette; and (iv) optionallyattaching a cigarette filter to the tobacco rod using tipping wrapper.In cigarette production, a wrapper is wrapped around cut filler to forma tobacco rod portion of the cigarette by a cigarette-making machine,which has previously been supplied or is continuously supplied withtobacco cut filler and one or more ribbons of wrapper.

According to preferred methods, a high-temperature ammonia-release agentis incorporated in tobacco cut filler and/or a cigarette wrapper thatare used to form a lit-end cigarette. By incorporating ahigh-temperature ammonia-release agent into one or more components of acigarette, the high-temperature ammonia-release agent can decrease thecytotoxicity of particulate matter in mainstream smoke during smoking ofthe cigarette.

Preferably, the high-temperature ammonia-release agent is incorporatedin tobacco cut filler and/or a cigarette wrapper in an amount effectiveto decrease the cytotoxicity of particulate matter in mainstream smokeby at least 5% (e.g., by at least 15%, 20%, 25%, 30%, 35%, 40%, 45%,50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or 95%) compared to acigarette without the high-temperature ammonia-release agent. Apreferred amount of the high-temperature ammonia-release agent percigarette is about 100 microgram to 100 mg.

“Smoking” of a cigarette means the heating or combustion of thecigarette to form smoke, which can be drawn through the cigarette.Generally, smoking of a cigarette involves lighting one end of thecigarette and, while the tobacco contained therein undergoes acombustion reaction, drawing smoke from the combustion through the mouthend of the cigarette.

The term “mainstream” smoke refers to the mixture of gases passing downthe tobacco rod and issuing through the filter end, i.e., the amount ofsmoke issuing or drawn from the mouth end of a cigarette during smokingof the cigarette. The mainstream smoke contains smoke that is drawn inthrough both the lighted region, as well as through the cigarettewrapper. The term “sidestream” includes smoke given off into thesurrounding air that does not exit through the mouth end of thecigarette.

During smoking there are three distinct regions in a cigarette: thecombustion zone, the pyrolysis/distillation zone, and thecondensation/filtration zone. First, the combustion zone is the burningzone of the cigarette produced during smoking of the cigarette at thelighted end of the cigarette. The temperature in the combustion zoneranges from about 600° C. to about 950° C., and the heating rate can beas high as 500° C./second. The pyrolysis zone is the region behind thecombustion zone, where the temperature ranges from about 200° C. toabout 600° C. Finally, in the condensation/filtration zone thetemperature ranges from ambient to about 150° C.

Any conventional or modified cigarette making technique may be used toincorporate one or more high-temperature ammonia-release agents into acigarette. The cigarettes can be manufactured to any knownspecifications using standard or modified cigarette making techniquesand equipment. The cut filler composition, for example, is optionallycombined with other cigarette additives, and provided to acigarette-making machine to produce a tobacco column, which is thenwrapped in cigarette wrapper, and optionally tipped with filters.

Cigarettes may range from about 50 mm to about 120 mm in length. Thecircumference is from about 15 mm to about 30 mm in circumference, andpreferably around 25 mm. The tobacco packing density is typicallybetween the range of about 100 mg/cm³ to about 300 mg/cm³, andpreferably 150 mg/cm³ to about 275 mg/cm³.

While the invention has been described with reference to preferredembodiments, it is to be understood that variations and modificationsmay be resorted to as will be apparent to those skilled in the art. Suchvariations and modifications are to be considered within the purview andscope of the invention as defined by the claims appended hereto.

All of the above-mentioned references are herein incorporated byreference in their entirety to the same extent as if each individualreference was specifically and individually indicated to be incorporatedherein by reference in its entirety.

What is claimed is:
 1. A tobacco smoking mixture, comprising: tobacco;and at least one high-temperature ammonia-release agent, wherein the atleast one high-temperature ammonia-release agent is an ammonium ironpyrophosphate.
 2. The tobacco smoking mixture of claim 1, wherein theammonium iron pyrophosphate comprises ammonium iron (III) pyrophosphateor mixtures thereof.
 3. The tobacco smoking mixture of claim 1, whereinthe at least one high-temperature ammonia-release agent is present in anamount effective to reduce the cytotoxicity of gas phase or particulatematter upon the combustion and/or pyrolysis of the tobacco smokingmixture up to about 50% by weight based on the total weight of thetobacco smoking mixture, and/or wherein the at least onehigh-temperature ammonia-release agent comprises particles of less thanabout 10 microns.
 4. The tobacco smoking mixture of claim 1, wherein theat least one high-temperature ammonia-release agent produces ammonia ata temperature of greater than about 200° C.
 5. The tobacco smokingmixture of claim 4, wherein the at least one high-temperatureammonia-release agent produces ammonia at a temperature of greater thanabout 600° C.
 6. The tobacco smoking mixture of claim 1, wherein the atleast one high-temperature ammonia-release agent is uniformlydistributed throughout the tobacco smoking mixture, and/or wherein theat least one high-temperature ammonia-release agent is present in anamount effective to reduce the cytotoxicity of gas phase or particulatematter upon the combustion and/or pyrolysis of the tobacco smokingmixture.
 7. A cigarette comprising a tobacco rod comprising the tobaccosmoking mixture of claim 1 and a paper wrapper.